It is conventional practice in the printing industry to remove waste liquids, inks or print-related substances from rollers using a blade of rubber or similar material the edge of which engages with the rotating roller to scrape the surplus material from the roller, the waste material then being directed into a wash-up tray.
The wash-up trays need to be cleaned regularly, and this can be a messy and time-consuming exercise which can result in undesirable exposure to, and contact with, printing waste and chemicals.
It has therefore been proposed, for example as disclosed in WO94/19193 and DE-U-92 00 319, to provide the wash-up tray with a liner which protects the wash-up tray and retains the waste material therein. On completion of the roller cleaning process, the liner and waste material are removed from the wash-up tray and are disposed of, a replacement liner then being inserted into the wash-up tray for subsequent collection purposes.
Conventionally, the liners were releasably attached to the blades by means of double sided adhesive tape. However, such an arrangement suffers from a number of disadvantages not the least of which is that, being prone to contact by chemicals, in particular solvents, the tape is liable to be degraded by the waste materials and to lose its adhesion, whereby the liner can become displaced from its operative position during the cleaning process.
It has been proposed, for example as disclosed in DE-U-8903674, to provide a thickened upper edge to the liner which is received in a slot formed in the lower regions of the blade to interconnect the liner and the blade. Such an arrangement simplifies attachment of the liner to, and release of the liner from, the blade.
However, there are still problems associated with removal of the liner from the tray when full of waste material because of the fluid nature of the waste material.